RTP Payload Format for Flexible Forward Error Correction (FEC)
draft-ietf-payload-flexible-fec-scheme-20

Document Type Active Internet-Draft (payload WG)
Last updated 2019-05-24 (latest revision 2019-05-16)
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PAYLOAD                                                        M. Zanaty
Internet-Draft                                                     Cisco
Intended status: Standards Track                                V. Singh
Expires: November 17, 2019                                  callstats.io
                                                                A. Begen
                                                         Networked Media
                                                              G. Mandyam
                                                           Qualcomm Inc.
                                                            May 16, 2019

     RTP Payload Format for Flexible Forward Error Correction (FEC)
               draft-ietf-payload-flexible-fec-scheme-20

Abstract

   This document defines new RTP payload formats for the Forward Error
   Correction (FEC) packets that are generated by the non-interleaved
   and interleaved parity codes from source media encapsulated in RTP.
   These parity codes are systematic codes (Flexible FEC, or "FLEX
   FEC"), where a number of FEC repair packets are generated from a set
   of source packets from one or more source RTP streams.  These FEC
   repair packets are sent in a redundancy RTP stream separate from the
   source RTP stream(s) that carries the source packets.  RTP source
   packets that were lost in transmission can be reconstructed using the
   source and repair packets that were received.  The non-interleaved
   and interleaved parity codes which are defined in this specification
   offer a good protection against random and bursty packet losses,
   respectively, at a cost of complexity.  The RTP payload formats that
   are defined in this document address scalability issues experienced
   with the earlier specifications, and offer several improvements.  Due
   to these changes, the new payload formats are not backward compatible
   with earlier specifications, but endpoints that do not implement this
   specification can still work by simply ignoring the FEC repair
   packets.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any

Zanaty, et al.          Expires November 17, 2019               [Page 1]
Internet-Draft      RTP Payload Format for Parity FEC           May 2019

   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on November 17, 2019.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Parity Codes  . . . . . . . . . . . . . . . . . . . . . .   4
       1.1.1.  One-Dimensional (1-D) Non-interleaved (Row) FEC
               Protection  . . . . . . . . . . . . . . . . . . . . .   5
       1.1.2.  1-D Interleaved (Column) FEC Protection . . . . . . .   6
       1.1.3.  Use Cases for 1-D FEC Protection  . . . . . . . . . .   7
       1.1.4.  Two-Dimensional (2-D) (Row and Column) FEC Protection   8
       1.1.5.  FEC Protection with Flexible Mask . . . . . . . . . .  10
       1.1.6.  FEC Overhead Considerations . . . . . . . . . . . . .  10
       1.1.7.  FEC Protection with Retransmission  . . . . . . . . .  10
       1.1.8.  Repair Window Considerations  . . . . . . . . . . . .  11
   2.  Requirements Notation . . . . . . . . . . . . . . . . . . . .  11
   3.  Definitions and Notations . . . . . . . . . . . . . . . . . .  11
     3.1.  Definitions . . . . . . . . . . . . . . . . . . . . . . .  11
     3.2.  Notations . . . . . . . . . . . . . . . . . . . . . . . .  12
   4.  Packet Formats  . . . . . . . . . . . . . . . . . . . . . . .  12
     4.1.  Source Packets  . . . . . . . . . . . . . . . . . . . . .  12
     4.2.  FEC Repair Packets  . . . . . . . . . . . . . . . . . . .  13
       4.2.1.  RTP Header of FEC Repair Packets  . . . . . . . . . .  13
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